The subject matter disclosed herein relates to a valve bypass and, more particularly, to a valve bypass for use with a lubrication (“lube”) system of, for example, an aircraft engine.
Aircraft lubricating systems often incorporate a system for pressurizing a lube pump suction above ambient pressure. This is especially important when the aircraft is designed to fly at high altitudes where the local air pressure is very low. The elevated suction pressure helps the pump fill with oil and prevents cavitation in the lube pump, which can damage the pumping elements. The pressurization is often accomplished by pressurizing the lube reservoir (i.e., the oil tank) by placing a pressure regulating valve on the tank that restricts the flow of air that exits the top of the tank's deaerator via a vent line. This elevates the pressure inside the tank, which then pressurizes the line from the tank that feeds the lube pump suction.
The air flowing along the vent line then passes to a de-oiler that is designed to remove oil droplets from the vent air flow. The de-oiler is effective at removing oil mist droplets when they are larger than a certain minimum size. Droplets smaller than this may pass through the de-oiler and exit via the vent line.